1. Field of the Invention
The present invention relates generally to post-mix beverage dispensing valves and, in particular, to post-mix beverage dispensing valves that automatically maintain the proper ratio of two beverage components.
2. Background of the Invention
Post-mix beverage dispensing valves that provide for the proper ratioing of a mixture of, for example, carbonated water and syrup to produce a dispensed beverage, are well known in the art. Such prior art valves generally consist of a valve body having separate channels therethrough for the delivery of beverage constituents separately to a valving mechanism for ultimate delivery through a mixing nozzle to a suitable receptacle. To provide for the proper beverage mixture, post-mix beverage dispensing valves of this type include flow controls in each of the beverage constituent lines. The flow controls are generally of the piston, needle valve or flow washer type. When properly adjusted, such flow controls maintain the desired ratio or brix quite well. However, it has been found that differences in ambient temperature, the delivery pressures of the drink constituents and mechanical wear of the flow controls can contribute to an improperly mixed drink.
A mechanical approach to automatic brix control is known wherein doubling acting pistons are linked together so they operate simultaneously. The proper ratio is maintained whereby the volumes of the pistons are at the desired ratio, typically five to one for a mixture of carbonated water and syrup. In this manner, five volumes of water and one volume of syrup are pumped for each stroke of the pistons in each direction. This approach works relatively well when large volumes of, for example, water and syrup are mixed. Difficulties have been experienced with respect to reduction in size sufficient to fit within the dimensions of a typical post-mix dispensing valve. In addition, such a system has proven to be expensive to manufacture.
Other automatic ratioing approaches have been proposed wherein the ambient temperature and/or pressures of the beverage constituents are independently monitored and adjusted accordingly. However, such systems suffer primarily from complexity and high cost.
Accordingly, it would be highly desirable to have a post-mix beverage dispensing valve that automatically maintains the desired ratio of beverage constituents and that is easy and inexpensive to manufacture and operate.